The “nonpeptidic pharmaceutically active ingredient having a primary or secondary amino group” is widely used as a pharmaceutically active ingredient for various diseases. For example, patent document 1 describes a compound represented by the following formula and a salt thereof as agents for the treatment or prophylaxis of peptic ulcer, gastritis, erosive esophagitis and the like.
wherein r1 is a monocyclic nitrogen-containing heterocyclic group optionally condensed with a benzene ring or a heterocycle, the monocyclic nitrogen-containing heterocyclic group optionally condensed with a benzene ring or a heterocycle optionally has substituent(s), r2 is an optionally substituted C6-14 aryl group, an optionally substituted thienyl group or an optionally substituted pyridyl group, r3 and r4 are each a hydrogen atom, or one of r3 and r4 is a hydrogen atom, and the other is an optionally substituted lower alkyl group, an acyl group, a halogen atom, a cyano group or a nitro group, and r5 is an alkyl group.
Patent document 2 describes a proton pump inhibitor (PPI) comprising a compound represented by the following formula or a salt thereof, or a prodrug thereof as an agent for the treatment or prophylaxis of peptic ulcer, gastritis, erosive esophagitis and the like.
wherein Z and W are the same or different and each is a bond or a spacer having 1 to 20 atoms in the main chain, r6 is an optionally substituted hydrocarbon group or an optionally substituted heterocyclic group, r7, r8 and r9 are the same or different and each is a hydrogen atom, an optionally substituted hydrocarbon group, an optionally substituted thienyl group, an optionally substituted benzo[b]thienyl group, an optionally substituted furyl group, an optionally substituted pyridyl group, an optionally substituted pyrazolyl group, an optionally substituted pyrimidinyl group, an acyl group, a halogen atom, a cyano group or a nitro group, and r10 and r11 are the same or different and each is a hydrogen atom or an optionally substituted hydrocarbon group.
Patent document 3 describes N-(1-octyl-5-carboxymethyl-4,6-dimethylindolin-7-yl)-2,2-dimethylpropaneamide (the following formula) or a pharmacologically acceptable salt thereof as an active ingredient of a stabilized pharmaceutical composition containing an indoline compound.

Patent document 4 describes, as an improved preparation for oral use of a compound, a pharmaceutical composition for oral administration, which comprises at least a) ethyl 3-[(2-{[4-(hexyloxycarbonylamino-imino-methyl)-phenylamino]-methyl}-1-methyl-1H-benzoimidazole-5-carbonyl)-pyridin-2-yl-amino]-propionate represented by the following formula or one of the pharmaceutically acceptable salts thereof and b) one or more pharmaceutically acceptable organic acids having water-solubility higher than 1 g/250 ml at 20° C.

On the other hand, regarding a stabilizer of a pharmaceutically active ingredient in a pharmaceutical composition, patent document 5 discloses an aqueous pharmaceutical solution comprising an aqueous solution containing an organic acid salt of a polymyxin antibiotic and carboxylic acid (organic acid, as a stabilizer).
In addition, non-patent document 1 describes, for stabilization of peptide (P66) in a nonaqueous solvent, acidification of peptide by addition of HCl, TFA, H3PO4 and the like.
Beside the above, patent document 6 describes a pharmaceutical composition comprising a proton pump antagonist (acid pump antagonist, APA) and one or more basic excipients to stabilize APA, and patent document 7 describes a sustained-release pharmaceutical composition comprising reversible PPI, wherein APA is stabilized with one or more basic excipients (carbonate, magnesium salt etc.).
Patent document 8 discloses a stabilized pharmaceutical preparation coated with a coating agent containing a) a light shielding agent capable of generating free radical by UV light, and b) a free radical scavenger. In addition, as the light shielding agent capable of generating free radical by UV light, metal oxides such as titanium oxide and the like are described, and as the free radical scavenger, for example, organic acids such as benzoic acid and the like are described.
In addition, non-patent document 2 describes the principles of photocatalytic reaction of titanium oxide, and explains the Honda Fujiyama effect that various substances adsorbed to a photocatalytic surface are oxidized and reduced when titanium oxide, which is one kind of the photocatalysts, is exposed to a light having a wavelength of 380 nm or below.